Environment and Ecology: UPSC Previous Year Questions (Prelims)
259 previous year UPSC Prelims Environment and Ecology questions are on this page, from 1996 to 2025, in 10 chapters. Species, Pollution, Environmental Laws and Conventions and Climate Change are the largest, and recent papers lean on statement-pairs about news items: Direct Air Capture, the Nature Restoration Law, PFAS and the Peacock tarantula. Filter by chapter to revise one area, or by year for a single paper.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 131–140 of 259 questions
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UPSC 2017Environment and Ecology · Agriculture and Environment
Q131. Which of the following statements can help in water conservation in agriculture? 1. Reduced or zero tillage of the land 2. Applying gypsum before irrigating the field 3. Allowing crop residue to remain in the field Select the correct answer using the code given below:
Explanation
Efficient water use in agriculture refers to practices and techniques that aim to maximize the productivity of crops while minimizing water consumption. It involves employing methods such as capturing and storing water and drip irrigation to deliver water directly to the plant roots, reducing losses due to evaporation or runoff. Statements 1 and 3 are correct: Conservation Tillage includes no-till farming or zero tillage which is a way of growing crops or pasture from year to year without disturbing the soil through tillage. Zero tillage helps in soil moisture conservation. Crop residues act as mulches and reduce evaporation losses and protect the soil from direct impact of raindrops, thus controlling crusting and sealing processes.
Statement 2 is incorrect: Though, Gypsum helps in dissolution of the salt clay pan found in soils that hinder the percolation of water and helps in water conservation.
UPSC 2017Environment and Ecology · Pollution
Q132. Biological Oxygen Demand (BOD) is a standard criterion for:
Explanation
BOD measures the amount of dissolved oxygen required by microorganisms to break down organic material in water over a specific time. BOD is the amount of dissolved oxygen needed by bacteria in decomposing the organic wastes present in water. It is measured in milligrammes per litre of water of oxygen. The higher value of BOD indicates low (Dissolved Oxygen) DO content of water. BOD is not a reliable method for assessing water pollution because it only includes biodegradable elements.
Additional insight:
Standard Method 5210B is the most widely used method for determining Biological Oxygen Demand (BOD). It measures the difference in dissolved oxygen (DO) over a five-day incubation period at 20°C. The initial DO is recorded, and after incubation, the final DO is measured. The BOD value is then calculated based on oxygen depletion. Higher BOD indicates poor water quality due to higher oxygen demand, while lower BOD suggests purer water with less oxygen consumption. DO levels are lower in summer as warm water holds less oxygen.
UPSC 2017Environment and Ecology · Pollution
Q133. In the context of solving pollution problems, what is/are the advantage/advantages of bioremediation techniques? 1. It is a technique for cleaning up pollution by enhancing the same biodegradation process that occurs in nature. 2. Any contaminant with heavy metals such as cadmium and lead can be readily and completely treated by bioremediation using microorganisms. 3. Genetic engineering can be used to create microorganisms specifically designed for bioremediation. Select the correct answer using the code given below:
Explanation
Bioremediation is a branch of biotechnology that employs the use of living organisms in the removal of contaminants, pollutants, and toxins from soil, water, and other environments. These organisms can include microbes and bacteria. As a result, compared to other cleanup techniques, bioremediation causes less disruption to the neighbourhood communities.
Statement 1 is correct: Bioremediation uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances.
Statement 2 is incorrect: Not all contaminants are easily treated by bioremediation using microorganisms. For eg. Heavy metals such as cadmium and lead are not readily absorbed or captured by microorganisms.
Statement 3 is correct: The use of genetic engineering to create organisms specifically designed for bioremediation has great potential. For e.g. Alcanivorax, a bacteria with oil-eating abilities, can be used to create species that are much more capable of cleaning oil spills.
Additional insight:
Types of Bioremediation:
Aerobic Bioremediation: Requires oxygen for microbial reactions, where bacteria use a carbon substrate as an electron donor and oxygen as the electron acceptor to break down contaminants. Anaerobic Bioremediation: Occurs in the absence of oxygen, using alternatives like nitrate, sulfate, or carbon dioxide as electron acceptors. Processes include fermentation, methanogenesis, and reductive dechlorination to degrade pollutants. Cometabolic Bioremediation: Microbes degrade contaminants without gaining energy or carbon from them, breaking down pollutants as a side reaction while metabolizing other substances.
Exam tip:
For S2, "Readily and Completely" treated- it is Clearly an extreme phrase, hence very unlikely to be true. If this would have been true, water and soil pollution would have been talk of past, but that’s not the case, hence likely false. Eliminating options B and D.
UPSC 2017Environment and Ecology · Pollution
Q134. It is possible to produce algae based biofuels, but what is/are the likely limitation(s) of developing countries in promoting this industry? 1. Production of algae based biofuels is possible in seas only and not on continents. 2. Setting up and engineering the algae based biofuels production requires high level of expertise/ technology until the construction is complete. 3. Economically viable production necessitates the setting up of large scale facilities which may raise ecological and social concerns. Select the correct answer using the code given below:
Explanation
Biofuels are hydrocarbon fuel that is created in a short amount of time--days, weeks, or even months--from organic matter (living or once-living material). Biofuels may be solid, liquid or gaseous in nature:
Solid: Wood, dried plant material, and manure Liquid: Bioethanol and Biodiesel Gaseous: Biogas
Statement 1 is incorrect: Algaculture (farming algae) can be initiated on land unsuitable for agriculture or saline water or wastewater. Statements 2 and 3 are correct: Producing algae for biofuels (excluding simple seaweed production) requires significant capital investments, which may be a significant barrier in developing countries that have a weak investment climate. Also during the setup stage, the production of algae- based biofuels will necessitate expertise in advanced technology.
Exam tip:
For S1, "seas ONLY" is an extreme absolute phrase and hence unlikely to be true. Thus eliminate options A and D. In contrast, S 2 and S3 are too general and practical to be false, hence more likely to be true.
UPSC 2017Environment and Ecology · Climate Change
Q135. In the context of mitigating the impending global warming due to anthropogenic emissions of carbon dioxide, which of the following can be potential sites for carbon sequestration? 1. Abandoned and uneconomic coal seams 2. Depleted oil and gas reservoirs 3. Subterranean deep saline formations Select the correct answer using the code given below:
Explanation
Carbon Sequestration is a process to capture and store CO₂ to curb global warming. It is captured from the air, industries or power stations and stored permanently underground. Terrestrial Carbon Sequestration is the process through which CO₂ from the atmosphere is absorbed by trees and plants through photosynthesis and stored as carbon in soils and biomass (tree trunks, branches, foliage, and roots). In Geologic Carbon Sequestration CO₂ can be stored in oil reservoirs, gas reservoirs, unmineable coal seams, saline formations and shale formations with high organic content.
Statement 1 is correct: Uneconomic coal seams can be used to store CO₂ because the CO₂ molecules attach to the surface of coal.
Statement 2 is correct: CO₂ is sometimes injected into declining oil fields to increase oil recovery.
Statement 3 is correct: Other potential sites are gas reservoirs, saline formations and shale formations with high organic content.
UPSC 2017Environment and Ecology · Environmental Laws, Conventions and Policies
Q136. Recently there was a proposal to translocate some of the lions from their natural habitat in Gujarat to which one of the following sites?
Explanation
The proposal to translocate some of the lions from their natural habitat in Gujarat was aimed at establishing a second population of Asiatic lions in Kuno Palpur Wildlife Sanctuary in Madhya Pradesh. This initiative is part of the Asiatic Lion Reintroduction Project, which seeks to ensure the genetic stability and conservation of the species. The last wild population of the Asiatic lion is found in the region of Gir Forest National Park, in the state of Gujarat.
UPSC 2017Environment and Ecology · Environmental Laws, Conventions and Policies
Q137. In India, if a species of tortoise is declared protected under Schedule I of the Wildlife (Protection) Act, 1972, what does it imply?
Explanation
Schedule I of the Wildlife (Protection) Act, 1972 covers endangered species that need rigorous protection. The species are granted protection from poaching, killing, trading etc. Wildlife (Protection) Act, 1972 was passed in order to safeguard various plant and animal species. Some of the animals granted protection under the Schedule I include, Black Buck, Tiger, Clouded Leopard, Snow Leopard, Swamp Deer, Himalayan Bear, Asiatic Cheetah, Kashmiri Stag, Fishing Cat, Lion-tailed Macaque, Musk Deer, Rhinoceros, Brow Antlered Deer, Chinkara (Indian Gazelle), Capped Langur, Golden Langur, Hoolock Gibbon etc. Species declared protected under Schedule I are prohibited to be hunted throughout India, except under threat to human life or in case of a disease that is beyond recovery. Thus tortoise species declared under Schedule I enjoys the same level of protection as iconic species like the tiger and elephant. Note: Updated schedules have been added in the vermin question of 2024.
UPSC 2017Environment and Ecology · Environmental Laws, Conventions and Policies
Q138. According to the Wildlife (Protection) Act, 1972, which of the following animals cannot be hunted by any person except under some provisions provided by law? 1. Gharial 2. Indian wild ass 3. Wild buffalo Select the correct answer using the code given below:
Explanation
Under the Wildlife (Protection) Act, 1972, certain species are granted varying levels of protection through classification into different schedules. Species listed in Schedule I receive the highest level of protection, prohibiting hunting except under specific circumstances such as threat to human life, if the animal is disabled or diseased beyond recovery or for scientific research. The Gharial (Gavialis gangeticus), a critically endangered crocodilian, is listed under Schedule I, providing it with stringent protection measures. The Indian Wild Ass (Equus hemionus khur), found primarily in the Rann of Kutch, is also listed under Schedule I, ensuring its protection. The Wild Buffalo (Bubalus arnee), native to parts of central India, is included in Schedule I, reflecting its endangered status and the need for strict conservation efforts. Note: Updated schedules have been added in the vermin question of 2024."
UPSC 2017Environment and Ecology · Environmental Organisations
Q139. With reference to ‘Global Climate Change Alliance’, which of the following statements is/are correct? 1. It is an initiative of the European Union. 2. It provides technical and financial support to targeted developing countries to integrate climate change into their development policies and budgets. 3. It is coordinated by World Resources Institute (WRI) and World Business Council for Sustainable Development (WBCSD). Select the correct answer using the code given below:
Explanation
Global Climate Change Alliance (GCCA) operates through the existing national and international channels for political cooperation and dialogue. It became the main project of the Global Climate Change Alliance Plus (GCCA+) in 2015 with strategic focus on promoting the 2015 Paris Agreement on Climate Change, the 2030 Agenda for Sustainable Development, and its Sustainable Development Goals.
Statement 1 is correct: The Global Climate Change Alliance (GCCA) is an initiative of the European Union.
Statement 2 is correct: It was launched to enhance dialogue and cooperation on climate change, this initiative focuses on supporting developing countries, particularly Least Developed Countries (LDCs) and Small Island Developing States (SIDS), which are most vulnerable to its effects. It provides technical and financial assistance to help these nations integrate climate change into their development strategies and budgets.
Statement 3 is incorrect: The World Resources Institute (WRI) is a global research organization focused on the intersection of environment, economic opportunity, and human well-being. The World Business Council for Sustainable Development (WBCSD) is a CEO-led community of over 200 sustainable businesses working towards a net-zero, nature-positive, and equitable future. Both WRI and WBCSD drive private-sector sustainability initiatives like the Greenhouse Gas Protocol, but they are not directly linked to the Global Climate Change Alliance (GCCA).
Exam tip:
For S3, aligns with Function-person/organisation/ministry match trap as its easy to manipulate to make it false. World Business Council doing Global climate change alliance? Unlikely!
UPSC 2017Environment and Ecology · Environmental Organisations
Q140. Consider the following statements: 1. Climate and Clean Air Coalition (CCAC) to Reduce Short Lived Climate Pollutants is a unique initiative of G2O group of countries. 2. The CCAC focuses on methane, black carbon and hydrofluorocarbons. Which of the statements given above is/are correct?
Explanation
Climate and Clean Air Coalition (CCAC) is a voluntary alliance of governments, intergovernmental organisations, corporations, academic institutions, and organisations from civil society dedicated to enhancing air quality and defending the environment by taking steps to reduce short-lived climate pollutants.
Statement 1 is incorrect: The United Nations Environment Programme (UNEP), the governments of Bangladesh, Canada, Ghana, Mexico, Sweden, and the United States joined forces in 2012 to launch initiatives to handle short-lived climate pollutants as an urgent and collective concern. CCAC is not an initiative of G20 countries.
Statement 2 is correct: CCAC works to reduce Short-Lived Climate Pollutants which includes black carbon, methane, tropospheric ozone, and hydrofluorocarbons. By addressing these pollutants, the coalition aims to achieve near-term climate benefits, improve air quality, and promote public health.
Answer key for these questions
Q
UPSC year
Correct answer
131
2017
(c) 1 and 3 only
132
2017
(c) Pollution assay in aquatic ecosystems
133
2017
(c) 1 and 3 only
134
2017
(b) 2 and 3 only
135
2017
(d) 1, 2 and 3
136
2017
(b) Kuno Palpur Wildlife Sanctuary
137
2017
(a) It enjoys the same level of protection as the tiger.
138
2017
(d) 1, 2 and 3
139
2017
(a) 1 and 2 only
140
2017
(b) 2 only
What UPSC has tested in Environment and Ecology
Species questions ask for classification and habitat: which is an insect, a filter feeder, or not a bird, and where an animal is found.
Law and convention questions ask which body or instrument covers what, such as the Wildlife Protection Act’s schedules, the e-Waste Rules and the Ramsar Convention.
Climate questions in 2025 covered Article 6 of the Paris Agreement, COP28, Direct Air Capture and wet-bulb temperatures.
Protected-area questions combine locations with distinctive features, such as the swamp park of Keibul Lamjao and Critical Tiger Habitats.
Frequently asked questions
How many previous year UPSC questions are there on Environment and Ecology?
This page covers 259 previous year UPSC Prelims GS Paper-I questions on Environment and Ecology, asked from 1996 to 2025. Each has the correct answer and an explanation.
Which Environment chapters have the most questions?
Species has the most with 43 questions, followed by Pollution and Environmental Laws, Conventions and Policies with 39 each, and Climate Change with 30. Environmental Organisations and Miscellaneous are the smallest.
How can I revise Environment and Ecology using these questions?
Take a chapter at a time with the Chapter filter, attempt the questions and read the facts UPSC has tested. Revise Species and Protected Areas with a map and a list of national parks at hand.
Are the 2025 Environment questions included?
Yes. The 2025 paper’s Environment questions on activated carbon, cement emissions, COP28, Article 6, Direct Air Capture, the Gooty tarantula, plastics and the Nature Restoration Law are included with full explanations.
